Rotating couplings that connect a drive unit to a driven unit are known in the art. These rotating couplings provide the connection that enables the drive unit to drive the driven unit. On occasion, these rotating couplings will be subjected to a dramatic shear event. For example, a generator may experience a short circuit causing a sudden stop in its rotation. The drive unit connected to the generator, however, is still rotating the coupling which subjects the coupling, and the connected equipment, to a sudden, high torsional shear event.
Historically, there have been two ways of designing rotating couplings to handle such shear events at typical motor speeds (e.g., up to about 3,600 rpm). First, the couplings, and the connected equipment, have been sized so that they are sufficiently strong that they can withstand the torsional shear encountered in a shear event. Of course, this can mean dramatically increasing the size and weight of the coupling components and equipment components.
Another way of designing the coupling components to handle a shear event, and help protect connected equipment, has been to include a frangible element in association with one of the existing coupling components. For example, flanges of two of the rotating coupling components can be connected using frangible bolts which shear upon encountering a shear event. As another example, a shear groove can be located in one of the existing components along which the component will separate during a shear event.
Neither of these solutions have resulted in a coupling capable of operating at high speeds to handle a shear event. As indicated above, the previous couplings have typically operated at normal motor speed of less than about 3,600 rpm. Couplings operating at high speed, e.g., above about 4,000 rpm or above about 5,000 rpm, have been unable to successfully use the methods described above to handle a shear event.
For example, couplings having a size sufficient to handle a high-speed shear event are typically too massive to spin at high speeds. In addition, including frangible bolts or a frangible groove on existing coupling components can have a high tendency to send dangerous metal parts flying, particularly at high speeds. Further, the use of a frangible groove in an existing coupling component can require replacement of an unnecessarily large component and/or significant down time depending upon, for example, where it is located in the coupling assembly. Accordingly, it is desirable to provide a coupling design that is capable of handling a shear event, even at high speeds, without one or more of the problems associated with previous designs, including, for example, one or more of the problems specifically identified above.